en Related Fields Related Fields مقاله کامل Full Length/Original Article <strong>Background: </strong><strong>&nbsp;</strong>Magnetotactic bacteria are a heterogeneous group of Gram-negative prokaryote cells that produce linear chains of magnetic particles called magnetosomes, intracellular organelles composed of magnetic iron particles. Many important applications have been defined for magnetic nanoparticles in biotechnology, such as cell separation applications and &nbsp;acting as carriers of enzymes, antibodies or anti-cancer drugs. Since the bacterial growth is difficult and the yield of magnetosome production is low, the application of magnetosome has not been developed on a commercial scale. <strong>Methods:</strong> <em>Magnetospirillum gryphiswaldense</em> strain MSR-1 was used in a modified current culture medium supplemented by different concentrations of oxygen, iron, carbon, and nitrogen, to increase the yield of magnetosomes. <strong>Results:</strong> Our improved MSR-1 culture medium increased magnetosome yield, magnetosome number per bacterial cell, magnetic response, and bacterial cell growth yield significantly.&nbsp; The yield of magnetosome increased approximately four times. The optimized culture medium containing 25 mM of Na-pyruvate, 40 mM of NaNO3, 200 &micro;M of ferrous sulfate, and 5-10 ppm of dissolved oxygen (DO) resulted in 186.67 mg of magnetosome per liter of culture medium.&nbsp; The iron uptake increased significantly, and the magnetic response of the bacteria to the magnetic field was higher than threefold as compared to the previously reported procedures. <strong>Conclusion: </strong>This technique not only decreases the cultivation time but also reduces the production cost. In this modified method, the iron and DO are the major factors affecting the production of magnetosome by <em>M. gryphiswaldense </em>strain MSR-1. However, refining this technique will enable a further yield of magnetosome and cell density. Conditioned culture medium, Magnetosomes, Magnetospirillum gryphiswaldense MSR-1 209 219 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-773&slc_lang=en&sid=1 Leila Hatami-Giklou Jajan 0000-0001-5266-9599 No Department of Research and Development, Research and Production Complex, Pasteur Institute of Iran, Karaj, Iran Seyed Nezamedin Hosseini 0000-0002-1457-0974 No Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran Masoud Ghorbani 0000-0002-4299-028X No Hybridoma Lab., Department of immunology, Pasteur Institute of Iran, Tehran, Iran Seyed Fazlollah Mousavi 0000-0003-3671-9378 No Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran Behzad Ghareyazie 0000-0001-8804-2931 No Agriculture Biotechnology Research Institute of Iran (ABRII), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran; Mohsen Abolhassani 0000-0003-1340-5114 Yes Hybridoma Lab., Department of immunology, Pasteur Institute of Iran, Tehran, Iran